Analysis of dissipation induced by successive planar shock loading of granular explosive

Document Type

Conference Proceeding

Publication Date

1-1-2015

Abstract

Shock compaction of granular explosives can trigger combustion that results in detonation, even for relatively mild shocks. It is well established that a primary (or lead) shock can desensitize the material to subsequent shocks by reducing porosity. This phenomenon, referred to as shock desensitization, has been observed to occur during Deflagration-to-Detonation Transition (DDT) of low density granular explosives in which complex inteactions between impact and combustion-supported shocks influence the initiation process. In this study, a computational analysis is performed to characterize how rapid successive shock loading of low density HMX (C4H8N8O8, 68-85% TMD) affects dissipation and igni- tion associated with the onset of vigorous burn. Meso-scale simulations are used to predict effective shock profiles and to examine hot-spot fields induced by pore collapse. Resolved shock profiles are compared to those given by an independent macro-scale compaction theory, and both are analyzed in a thermodynamic space that highlights desensitization effects. History-variable ignition models based on the variation in hot-spot formation frequency with shock strength are formulated for use with the macro-scale theory to examine how successive shock loading can influence the induction period prior to ignition. A history variable based on shock-induced dissipative work is shown to result in ignition fields that qualitatively differ from those based on shock pressure.

Publication Source (Journal or Book title)

51st AIAA/SAE/ASEE Joint Propulsion Conference

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